This invention relates to endoscopes and more particularly to electronic endoscopes.
Generally, endoscopes are instruments for visualizing the interior of an object, such as the human body (e.g., an internal organ or anatomical body passage). A typical endoscope includes an elongated flexible or rigid outer tube within which a lens system is disposed at a distal end. The image of the object being viewed by the optical system is transmitted through an optical system from the distal end to a proximal end of the tube for viewing by the user or for reception by a camera. Some endoscopes also carry fiber optic cables for illuminating the area of observation with light supplied by an external source.
In some endoscopes, the optical system includes a bundle of fibre optic cables positioned immediately proximally of a stationary objective lens assembly located at the distal end of the tube. The lens assembly focuses the image into the end of the fibre bundle, which in turn transmits the image proximally.
An electronic endoscope typically includes an electro-optic image sensor (such as a charge coupled device or CCD) in place of the fibre optic bundle. The CCD is positioned closely adjacent the objective lens assembly and generates a video signal of the object being observed. The video signal is transmitted by an electrical cable to the proximal end of the endoscope and is processed for viewing on a display such as a CRT monitor.